Graded transmitted wave structure in microwave sintering and method for preparing ceramic material using the same

Abstract

The invention relates to a gradient wave-transmitting structure used for microwave sintering and a method used for preparing ceramic materials, which are characterized in that: (1) when a material with high dielectric property is sintered, at least a transition layer is added into the exterior of the material and the transition layer is composed of high-efficient wave absorption material with certain concentration and a microwave transparent thinner; when a multilayered structure is used as the transition layer, the concentration of the high-efficient wave absorption material increases from exterior to interior in sequence; (2) when a material with low dielectric and relatively poor wave absorption properties is sintered, the multilayered structure is adopted for an exothermic material ora coat, wherein, the concentration of the high-efficient wave absorption material increases from exterior to interior in sequence and then decreases so as to be favorable for transmitting microwave. In the invention, energy consumption caused by a plurality of times of reflection and wave-absorbing and heat-emitting of a thermal insulating layer are reduced by improving the efficiency of being sintered and wave absorption, thus being capable of effectively realizing the purpose of increasing sintering temperature. In addition, the gradient thermal insulating structure can help materials sintered to obtain an even temperature field and better sintering quality.

Description

technical field [0001] The invention relates to a gradient wave-permeable structure in microwave sintering and a method for preparing ceramic materials, belonging to the field of microwave sintering ceramic materials. Background technique [0002] Compared with the traditional resistance heating method, the use of microwave sintering method can produce ceramic materials faster, better and save a lot of energy. However, the microwave field provided by the widely used multi-mode cavity sintering equipment is not uniform, and due to factors such as the size and shape of the material, it is easy to generate excessive temperature gradients, hot spots, thermal runaway and other problems at different positions of the material. resulting in sintering failure. In the microwave sintering process, there are other factors that also generate a temperature gradient in the sample. For example, when the sample is sintered in a microwave transparent crucible, the inner surface of the crucib...

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Problems solved by technology

No matter according to the US5,432,325 to make the container with the absorbing material, or according to the US5,736,092 proposed to use the absorbing material as the embedding powder, or let the absorbing sintered material directly contact with the microwave, the microwave directly hits the high dielectric constant When the material is on the surface, strong microwave reflections will occur on the surface, which will cause multiple reflections in the furnace cavity, increase the heat-absorbing materials such as thermal insulation materials, reduce the microwave energy absorbed by the sintered object, and affect the heating rate and heating limit value

[0008] Although the importance of the microwave reflection problem has not been recognized theoretically, the existing research on microwave technology has proved the existence of this problem from the side.

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